1. Field of the Invention
The present invention relates to a precision router guide, and more particularly, to a novel and improved method and apparatus for accurately guiding a router in the formation of grooves, slots, steps or other cutaway sections of various widths, such as in the construction of wooden shelving for edge-wise joining of the shelves thereto and therein.
2. Description of the Prior Art
Carpentry work frequently requires the precise formation of the tongue and groove or dado joint which provides a strong joining means for perpendicular configurations. The rabbet joint used for corner applications may be considered as a one sided dado joint and is formed in a similar manner. Both of these joints are commonly formed with the dado head cutter in conjunction with a table saw or radial arm saw. While this means is acceptable for high production precision applications, it lacks the portability, flexibility, safety and economy that is required by many carpenters. The introduction of the high speed router has made it possible to form dado and rabbet joints without these restrictions provided that a convenient guiding means could be developed.
Prior art devices that may be used to cut the rabbet and dado joints may be divided into two categories. The first category is composed of the decorative routing templates as illustrated in U.S. Pat. Nos. 4,062,123 and 3,875,670. These templates are comprised of a set of elongate bar members that are slidingly interconnected to form a rigid open frame configuration having a flat coplaner bottom that when attached to a work piece, may be used for guiding the routing tool thereover. Although these templates may be used for cutting dado and rabbet joints, they require excessive set up time and provide little advantage over a pair of individual straight edges. The second category of prior art devices is composed of those router guides that are specifically designed for cutting dado and rabbet joints as represented in U.S. Pat. Nos. 3,967,665 and 4,742,853. These router guides are composed of parallel guide members that may be movably adjusted by means of gauges whereby when correctly positioned and attached to the work piece, the router may be operably disposed between them so that the router is precisely positioned to cut the slot desired in the work piece. Because these devices provide guiding edges that are parallel and easily adjustable, they represent a significant improvement in the state of the art.
The second category of prior art devices are the most useful for cutting dado and rabbet joints, however these devices are expensive to manufacture due to the large number of special precision parts, and they tend to be heavy, and awkward to use. They also require complicated gauging procedures when locating the template on the work piece and setting the guide member spacing. Moreover, these devices utilize clamps which require access to the underside of the work piece, an arrangement that is inconvenient and undersirable. Because of these limitations in the prior art, router guides for cutting dado and rabbet joints are not widely used, and in fact, are generally unavailable. This situation will only be rectified if the state of the art is advanced to such an extent that these limitations are overcome.